Journal of Philosophical Logic

, Volume 38, Issue 1, pp 83–125

Everything Else Being Equal: A Modal Logic for Ceteris Paribus Preferences


DOI: 10.1007/s10992-008-9085-3

Cite this article as:
van Benthem, J., Girard, P. & Roy, O. J Philos Logic (2009) 38: 83. doi:10.1007/s10992-008-9085-3


This paper presents a new modal logic for ceteris paribus preferences understood in the sense of “all other things being equal”. This reading goes back to the seminal work of Von Wright in the early 1960’s and has returned in computer science in the 1990’s and in more abstract “dependency logics” today. We show how it differs from ceteris paribus as “all other things being normal”, which is used in contexts with preference defeaters. We provide a semantic analysis and several completeness theorems. We show how our system links up with Von Wright’s work, and how it applies to game-theoretic solution concepts, to agenda setting in investigation, and to preference change. We finally consider its relation with infinitary modal logics.


Ceteris paribusPreference logicModal logicDynamic logicPhilosophy of actionGame theory

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Johan van Benthem
    • 1
    • 2
  • Patrick Girard
    • 2
    • 3
  • Olivier Roy
    • 1
    • 4
  1. 1.Institute for Logic, Language and ComputationUniversity of AmsterdamAmsterdamThe Netherlands
  2. 2.Stanford UniversityStanfordUSA
  3. 3.University of AucklandAucklandNew Zealand
  4. 4.Faculty of PhilosophyUniversity of GroningenGroningenThe Netherlands